Fish Catch Relative to Environmental Parameters Observed from Satellite during ENSO and Dipole Mode Events 1997/98 in the South Java Sea

Abstract

The investigation is aimed to clarify the influence of the El Niño Southern Oscillation (ENSO) and the Dipole Mode (DM) events to the spatio-temporal evoluation of the sea surface temperature (SST) and Chlorophyll-a (Chl-a) as well as assessing of their impact to fish catchability. A time series of provincial montly averaged of SST and Chl-a derived from satellite data, are used in this investigation. Sardinella lemuru (Lemuru) and tuna fish catch are obtained from the fishery statictic data report and logbooks of ten fishing vessels operated in the south of Java seawaters. The SST indicated the coolest period with maximum anomalieswas obsrved during July-September 1997. Warmest period was during February-March 1998. It was occurred in Arafuru Sea and southeast off Lombok Strait (LS). The blooming of phytoplankton followed the coolest phase caused by upwelling at south of Java and southeast of Lombok Strait. The same condition was also observed on July-September 1999, but the scale and its quantity was different and smaller than on 1997. Monthly mean catch of Lemuru sharply increased during 1997-1998. The maximum of total catch and annual mean hook rate of tuna were highest during 1997 than 1998 and 1999. It seems have close correlation on the thermocline become shallower due to the DM-induced strong upwelling. Occurrence of thermal fronts around upwelling area might also have contributed to increase the fish catchability by providing suitable ambient temperature and feeding grounds for tuna.